The invention relates to a process for the preparation of an olefin polymerization catalyst component comprising a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- or polyester as internal electron donor. The invention also relates to such a catalyst component and its use for the polymerization of xcex1-olefins such as propene.
Generally, so called Ziegler-Natta catalyst components of the above kind have been prepared by reacting a magnesium halide-alcohol complex support with a titanium tetrahalide and an electron donor which usually is a phthalic acid di- oligo- or polyester. The preparation involves the use of large amounts of reagents and washing liquids, which are difficult to handle. Additionally, byproducts are formed, which cannot easily be regenerated or destroyed, but form an environmental problem.
For example, the preparation of a conventional polypropene catalyst component involves the reaction of a magnesium dichloride-alcohol complex support with titanium tetrachloride to give a surface layer of reactive xcex2-magnesium dichloride as intermediate and hydrogen chloride and titanium alkoxy trichloride as byproducts. Then, the surface layer of reactive xcex2-magnesium dichloride intermediate is activated with further titanium tetrachloride and optionally an internal electron donor to give said catalyst component (the treatment with a titanium halide such as titanium tetrachloride is henceforth called titanation). The result is an essentially inert magnesiumchloride based support covered with active sites based on titanium, chlorine and the optional internal electron donor.
The titanium alkoxy trichloride byproduct formed in such a titanation is a catalyst poison and must be carefully removed by extensive washing using large amounts of titanium tetrachloride. Further, the titanium alkoxy trichloride must be carefully separated from the titanium tetrachloride washing liquid, if the latter is to be reused e.g. for activating the reactive xcex2-magnesium dichloride. Finally, the titanium alkoxy trichloride is a hazardous waste material, which is difficult to dispose of.
Thus, in a typical propene polymerization catalyst component preparation involving two titanations and three heptane washes, one mol of produced catalyst component (mol Mg) requires about 40 mol of titanium tetrachloride e.g. as washing liquid to be circulated, and produces as waste material an amount of about three mol of titanium alkoxy trichloride as well as about three mol of hydrogen chloride.
Sumitomo, EP 0 748 820 A1 (hereinafter referred to as xe2x80x9cSumitomoxe2x80x9d), has prepared dialkoxy magnesium, reacted it with titanium tetrachloride to form an intermediate and then reacted the intermediate with phthalic acid dichloride to form a catalytically active propene polymerization catalyst component. The activity was raised by repeated titanations, as well as repeated washes with toluene and hexane. See page 10, lines 14 to 37, of said publication.
Said process of Sumitomo has avoided the reaction between the magnesium dichloride-alcohol complex and titanium tetrachloride, and thereby eliminated the formation of large amounts of catalytically poisonous titanium alkoxy trichloride byproduct. However, as much as four titanations and hydrocarbon treatments are still needed to give satisfactory catalytic activity.
The purpose of the present invention is to provide a process which results in a catalyst component having satisfactory activity without producing harmful byproducts such as said titanium alkoxy trichloride or requiring the use of large amounts of titanation reagent and/or washing liquid.
The problem described above has now been solved with a novel process for the preparation of a catalyst component of the above type, which is mainly characterized by the steps of:
(i) providing a magnesium compound (ab) containing an alkoxy moiety, selected from the group consisting of a magnesium dialkoxide, a complex containing a magnesium dihalide and an alcohol, and a complex containing a magnesium dihalide and a magnesium dialkoxide, and
(ii) reacting said magnesium compound (ab) with at least one dicarboxylic acid dihalide (c) which forms said dicarboxylic acid di-, oligo- or polyester as internal donor ED and has the formula (1): 
wherein each Rxe2x80x3 is a similar or different C1-C20 hydrocarbyl group or both Rxe2x80x3:s form together with the two unsaturated carbons of the formula a C5-C20 aliphatic or aromatic ring, and Xxe2x80x2 is a halogen, to give an intermediate (abc), and
(iii) reacting said intermediate (abc) with at least one titanium tetrahalide TiXxe2x80x34 (d) wherein Xxe2x80x3 is a halogen,
(iv) recovering said catalyst component in crude form or recovering a precursor of said catalyst component, and
(v) optionally washing said crude catalyst component or said precursor, to give said catalyst component, and
by adding and reacting in connection with the e step (ii) or (iii) at least one halogenated hydrocarbon (e) of the formula (2)
Rxe2x80x2xe2x80x3(Xxe2x80x2xe2x80x3)nxe2x80x83xe2x80x83(2)
wherein Rxe2x80x2xe2x80x3 is an n-valent C1-C20 hydrocarbyl group, Xxe2x80x2xe2x80x3 is a halogen and n is an integer selected from 1, 2, 3 and 4.
It has thus been found that a high activity olefin polymerization catalyst comprising a magnesium halide, a titanium tetrahalide and a dicarboxylic acid di-, oligo- or polyester as internal donor can be prepared without the above mentioned disadvantages by reacting a magnesium compound containing an alkoxy moiety with a dicarboxylic acid dihalide and a titanium tetrahalide and adding a reactive halogenated hydrocarbon.
Of the above mentioned steps (i) to (iii) preferably all are performed in solution. For dissolution of the reactants, one or several hydrocarbon solvents can be used, optionally together with the application of stirring and/or heating. Performing the process in a solution means that all reagent molecules can react with each other, thus forming a homogenous reaction product. Earlier processes which have been performed by reacting a solid support with a titanium compound and an electron donor, see above, do not form homogenous reaction products.
The catalyst component is in step (iv) preferably recovered in solid form by precipitation. Precipitation in the present invention means that the reaction product formed in solution is recovered as a powder, the particles of which consist of similar molecules of that reaction product. The particles formed according to the present invention are thus homogenous, while the particles of earlier processes are more or less heterogenous (inert core+active surface).
It is preferable if said first and second intermediates as well as the final product of the claimed process are separate compounds with an essentially stoichiometric composition. Often, they are complexes. A complex is, according to Rompps Chemie-Lexicon, 7. Edition, Franckh""sche Verlagshandlung, W. Keller and Co., Stuttgart, 1973, page 1831, xe2x80x9ca derived name of compounds of higher order, which originate from the combination of molecules,xe2x80x94unlike compounds of first order, in the creation of which atoms participate.
Reactive halogenated hydrocarbons (e) of the present invention are, e.g., monochloromethane, dichloromethane, trichloromethane (chloroform), tetrachloromethane, monochloroethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1-chloropropane, 2-chloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 1,2,3-trichloropropane, 1-chlorobutane, 2-chlorobutane, isobutyl chloride, tert.butyl chloride, 1,4-dichlorobutane, 1-chloropentane and 1,5-dichloropentane, as well as their corresponding compounds having other halogens. The chlorinated hydrocarbons of the invention may also be unsaturated, provided that the unsaturation does not act as catalyst poison in the final catalyst component.
In the invention, it was found that the addition of a reactive halogenated hydrocarbon (e) during the process led to a significantly improved catalytic activity. In said reactive halogenated hydrocarbon (e) having the above formula (2), Xxe2x80x2xe2x80x3 is preferably chlorine.
Rxe2x80x2xe2x80x3 is preferably a mono- or bivalent saturated C1-C10 hydrocarbyl group. Preferably said reactive halogenated hydrocarbon (e) is a butyl chloride (BuCl) or a dichloroalkane like 1,4-dichlorobutane, more preferably tertiary butyl chloride or a dichloroalkane like 1,4-dichlorobutane, most preferably a dichloroalkane like 1,4-dichlorobutane.
It was also found, that especially good results were obtained, if said reactive halogenated hydrocarbon (e) is added in an amount corresponding to a molar ratio Mgtotal added/(e) of between 1:0.2 and 1:20, preferably between about 1:1 and about 1:4.
Said reactive halogenated hydrocarbon (e) can be added in step (ii) or (iii). Preferably it is added in connection with step (ii). This means that in the process, it is preferably added immediately before the dicarboxylic acid dihalide (c), together with it or immediately after it. As there is a possibility that the reactive halogenated hydrocarbon (e) may disturb the conversion of the dicarboxyl di-halide into said dicarboxylic acid di-, oligo- or polyester donor, it is most preferably added immediately after the addition of the dicarboxylic acid dihalide (c). The symbols (ab) and (abc) may include the added or reacted reactive halogenated hydrocarbon (e). The symbols do not limit the reactants leading to the corresponding intermediates to (a), (b), (c) and (d).
The process according to the present invention starts with step (i), in which said magnesium compound (ab) containing an alkoxy moiety is provided. According to one embodiment, said complex of said magnesium dihalide and said magnesium dialkoxide as said magnesium compound (ab) is preferably a magnesium dichloride-magnesium alkoxide complex having the formula MgCl2.[Mg(OR)2]t, wherein R is a C1-C20 alkyl or a C7-C27 aralkyl, preferably a C6-C16 alkyl, and t is 1-6, preferably about 2. It is e.g. prepared by reacting magnesium dichloride MgCl2 with an alcohol ROH into an intermediate which is a magnesium dichloride/alcohol complex MgCl2.(ROH)2t and reacting the magnesium dichloride-alcohol complex with t mol of a magnesium dialkyl MgRxe2x80x2xe2x80x32, wherein Rxe2x80x2xe2x80x3 is a hydrocarbyl group having 1 to 20 carbon atoms.
Preferably, the complex of said magnesium dihalide and a magnesium dialkoxide as said alkoxy compound is a magnesium dichloride-dimagnesium dialkoxide complex having the formula MgCl2.[Mg(OR)2]2, wherein R is a C1-C20 alkyl or a C7-C27 aralkyl, preferably a C6-C16 alkyl. The complex may e.g. be prepared by reacting magnesium dichloride with an alcohol ROH and the obtained intermediate with a dialkyl magnesium Rxe2x80x2xe2x80x32Mg essentially as follows:
xe2x80x83MgCl2+4ROHxe2x86x92MgCl2.4ROH
MgCl2.4ROH+2MgRxe2x80x2xe2x80x32xe2x86x92MgCl2[Mg(OR)2]2+4Rxe2x80x2xe2x80x3H
In the reaction between the magnesium dihalide, the alcohol and the dialkyl-magnesium, the molar ratio MgCl2:ROH is preferably 1:1 to 1:8, most preferably 1:2 to 1.5. The molar ratio MgCl2.4ROH:MgRxe2x80x2xe2x80x32 is preferably 1:1 to 1:4, most preferably about 1:2. The temperature is preferably about 50xc2x0 C. to about 150xc2x0 C. and the reaction time preferably about 2 h to about 8 h. A hydrocarbon solvent such as toluene may be present in the reaction.
The magnesium compound (ab) is usually titaniumless. Most preferably, the magnesium compound (ab) is provided by reacting an alkyl magnesium compound and/or a magnesium dihalide with an alcohol. Thereby, at least one magnesium compound precursor (a), selected from the group consisting of a dialkyl magnesium R2Mg, an alkyl magnesium alkoxide RMgOR, wherein each R is a similar or different C1-C20 alkyl, and a magnesium dihalide MgX2, wherein X is a halogen, is reacted with at least one alcohol (b), selected from the group consisting of monohydric alcohols Rxe2x80x2OH and polyhydric alcohols Rxe2x80x2(OH)m, wherein Rxe2x80x2 is an 1-valent or, respectively, an m-valent C1-C20 hydrocarbyl group and m is an integer selected from 2, 3, 4, 5 and 6, to give said magnesium compound (ab). Rxe2x80x2 is the same or different in the formulas Rxe2x80x2OH and Rxe2x80x2(OH)m. By valence is understood the number of bonds that an atom can form (Stanley H. Pine, Organic Chemistry, 5. edition, McGraw-Hill, Inc., New York, 1987, page 10). The R of the dialkyl magnesium is preferably a similar or different C4-C12 alkyl. Typical magnesium alkyls are ethylbutyl magnesium, dibutyl magnesium, dipropyl magnesium, propylbutyl magnesium, dipentyl magnesium, butylpentylmagnesium, butyloctyl magnesium and dioctyl magnesium. Typical alkyl-alkoxy magnesium compounds are ethyl magnesium butoxide, magnesium dibutoxide, butyl magnesium pentoxide, magnesium dipentoxide, octyl magnesium butoxide and octyl magnesium octoxide. Most preferably, on R is a butyl group and the other R of R2Mg is an octyl group, i.e. the dialkyl magnesium compound is butyl octyl magnesium. When used as said magnesium compound precursor (a), the magnesium dihalide is preferably magnesium dichloride MgCl2.
The alcohol (b) of step (i) may be a monohydric alcohol, a polyhydric (by definition including dihydric and higher alcohols) alcohol or a mixture of at least one monohydric alcohol and at least one polyhydric alcohol. Magnesium enriched complexes can be obtained by replacing a part of the monohydric alcohol with the polyhydric alcohol.
Typical C1-C5 monohydric alcohols are methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, secbutanol, tert.butanol, n-amyl alcohol, iso-amyl alcohol, sec.amyl alcohol, tert.amyl alcohol, diethyl carbinol, akt. amyl alcohol, sec. isoamyl alcohol, tert.butyl carbinol. Typical C6-C10 monohydric alcohols are hexanol, 2-ethyl-1-butanol, 4-methyl-2-pentanol, 1-heptanol, 2-heptanol, 4-heptanol, 2,4-dimethyl-3-pentanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-nonanol, 5-nonanol, diisobutyl carbinol, 1-decanol and 2,7-dimethyl-2-octanol. Typical  greater than C10 monohydric alcohols are n-1-undecanol, n-1-dodecanol, n-1-tridecanol, n-1-tetradecanol, n-1-pentadecanol, n-1-hexadecanol, n-1-heptadecanol and n-1-octadecanol. The monohydric alcohols may be unsaturated, as long as they do not act as catalyst poisons. Preferable monohydric alcohols are those of formula Rxe2x80x2OH in which Rxe2x80x2 is a C2-C16 alkyl group, most preferably a C4-C12 alkyl group, like 2-ethyl-1-hexanol.
The amount of monohydric alcohol relative to the amount of magnesium compound precursor (a) may vary a lot, depending on the quality and quantity of the magnesium compounds, the dicarboxylic acid dihalide (c), the reactive halogenated hydrocarbon (e), is used and on whether the monohydric alcohol Rxe2x80x2OH is used alone or in combination with a polyhydric alcohol Rxe2x80x2(OH)m. The molar ratio Mg/Rxe2x80x2OH is preferably between about 1:5 and about 1:1, more preferably between about 1:4 and about 1:1, most preferably between about 1:2.5 and about 1:1.5.
Typical polyhydric alcohols are ethylene glycol, propene glycol, trimethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, pinacol, diethylene glycol, triethylene glycol, glycerol, trimethylol propane and pentaerythritol. According to one embodiment of the present invention, the polyhydric alcohol has the formula Rxe2x80x2(OH)m, wherein Rxe2x80x2 is a di-, tri- or tetravalent C2-C16 alkyl group and m is an integer selected from 2, 3, 4, 5 and 6. Preferably, Rxe2x80x2 is a divalent or a trivalent C2-C16 alkyl group and m is an integer selected from 2 and 3. Most preferably the polyhydric alcohol is selected from the group consisting of ethylene glycol, 2-butyl-2-ethyl-1,3-propanediol and glycerol.
In step (i) of the claimed process, it is preferable if at least one polyhydric alcohol Rxe2x80x2(OH)m is used, most preferably together with at least one monohydric alcohol Rxe2x80x2OH. Thereby, the molar ratio Mg/Rxe2x80x2(OH)m is preferably between about 1:1 and about 1:0.25, most preferably between about 1:0.8 and about 1:0.3.
The reaction conditions used in step (i) of the claimed process may vary according to the used reactants and agents. The conditions should be adjusted to give sufficiently of said magnesium compound (ab) between the magnesium compound precursor (a) and the alcohol(s) (b). According to an embodiment of the present invention, said magnesium compound precursor (a) is reacted with said at least one alcohol (b), under at least one of the following conditions:
at raised temperature, preferably at about 30xc2x0 C. to about 80xc2x0 C.,
for a period of about 10 min to about 90 min, preferably about 30 min,
in the presence of a C5-C10 hydrocarbon solvent, preferably heptane.
In addition to the above embodiments of step (i), other variations and reactions may also be used to produce said magnesium compound (ab), still being within the present scope of protection. Thus, with respect to step (i), the scope of protection should be interpreted under the doctrine of equivalence on the basis of what a skilled person could have done to achieve said intermediate (ab). E.g., the reaction between a tetra alkoxy silane and a dialkyl magnesium to give a magnesium dialkoxide (see Sumitomo, examples), is within the present scope of protection.
According to the invention, the product of step (i), or a similar composition, i.e. said magnesium compound (ab), is in a succeeding step (ii) reacted with a dicarboxylic acid dihalide (c) of the formula (1) to give an intermediate (abc), and said intermediate (abc) is in a third step (iii) reacted with a titanium tetrahalide TiXxe2x80x24 (d) wherein Xxe2x80x2 is a halogen.
The formula (1) of the dicarboxylic acid dihalide is: 
wherein each Rxe2x80x3 is a similar or different C1-C20 hydrocarbyl group or both Rxe2x80x2:s form together with the two unsaturated carbons seen in the formula a C5-C20 aliphatic or aromatic ring, and Xxe2x80x2 is a halogen.
Among non-cyclic dicarboxylic acid dihalides, the group consisting of maleic acid dihalide, fumaric acid dihalide and their Rxe2x80x9d substituted derivatives such as citraconic acid dihalide and mesaconic acid dihalide, respectively, are the most important. As the invention aims at to converting the dicarboxylic acid dihalides into their corresponding di-, oligo- or polyesters, and the di-, oligo- or polyesters as internal electron donors have to be coordinable with the magnesium dihalide and the titanium tetrahalide of the catalyst component, the cis-isomeric maleic acid dihalide and its derivatives, such as citraconic acid dihalide, are more advantageous.
However, in order to obtain a catalyst with exceptionally high activity, the Rxe2x80x2:s of formula (1) should form together with the two unsaturated carbons of the formula a C5-C20 aliphatic or aromatic ring. Among the cyclic dicarboxylic acid dihalides, the group consisting of phthalic acid dihalide (1,2-benzene dicarboxylic acid dihalide), its hydrogenate 1,2-cyclohexane dicarboxylic acid dihalide, and their derivatives, is the most important. Most preferably, said dicarboxylic acid dihalide (c) is phthaloyl dichloride.
The amount of the dicarboxylic acid dihalide (c) may vary a lot, depending on the amount of alcohol (b) used in step (i) and the amount of alkoxide present in said magnesium compound (ab) or in said alternative intermediate (abd). It is within the present scope to adjust the amounts in order to react said intermediates with said dicarboxylic acid dihalide. According to a preferred embodiment of the present invention, in step (ii), said magnesium compound (ab) is reacted with said dicarboxylic acid halide (c) in a molar ratio Mgtotal added/(c) of between 1:1 and 1:0.1, preferably between about 1:0.6 and about 1:0.25.
The reaction conditions of step (ii) of the claimed process may vary according to the used components and their amounts. However, they should be adjusted to give sufficiently of said reaction product (abc) between said magnesium compound (ab) and said dicarboxylic acid dihalide (c). According to an embodiment of the present invention, in step (ii), said magnesium compound (ab) is reacted with said dicarboxylic acid dihalide (c), under at least one of the following conditions:
adding said dicarboxylic acid dihalide (c) under room temperature and heating the obtained reaction mixture,
keeping the reactants together at raised temperature, preferably at about 30xc2x0 C. to about 80xc2x0 C.,
keeping the reactants together for a period of about 10 min to about 90 min, preferably about 30 min,
reacting the reactants in the presence of a C5-C10 hydrocarbon solvent, preferably heptane.
Usually, a C5-C10 hydrocarbon solvent is used in step (ii). Then, it is preferable, that, after said magnesium compound (ab) has been reacted with said dicarboxylic acid dihalide (c), the C5-C10 hydrocarbon solvent is removed by evaporation, e.g. that heptane is used and removed at about 100xc2x0 C. to about 110xc2x0 C.
As was said above, it is preferable to add said reactive halogenated hydrocarbon (e) in connection with and preferably after the dicarboxylic acid dihalide (c), i.e. at the end of step (ii). Most preferably, after said C5-C10 hydrocarbon solvent, preferably said heptane, has been removed by evaporation, said intermediate (abc) is contacted with said reactive halogenated hydrocarbon (e). A convenient contacting period is about 10 min to about 90 min, preferably about 30 min.
In this reaction sequence (i)xe2x86x92(ii)xe2x86x92(iii), after said intermediate (abc) has been contacted with said reactive halogenated hydrocarbon (e), preferably in step (ii), a dissolving C5-C10 hydrocarbon, such as toluene, is preferably added. Without limiting the scope of patent protection, the hydrocarbon is believed to dissolve the reaction product and/or to lower the viscosity of its solution, thus making the intermediate (abc, including (e)) more available for reaction with the titanium tetrahalide TiXxe2x80x34 (d) in the succeeding step (iii). Most preferably, a molar ratio Mgtotal added/toluene of between about 1:2 and about 1:10 is used in the addition.
In step (iii), the magnesium compound precursor/alcohol/dicarboxylic acid dihalide reaction product (abc) is reacted with at least one titanium tetrahalide TiXxe2x80x34 (d), wherein Xxe2x80x3 is a halogen. Equivalent with said titanium tetrahalide is the combination of an alkoxy titanium halide and a halogenation agent thereof, which are able to form a titanium tetrahalide in situ. However, the most preferred titanium tetrahalide (d) is titanium tetrachloride.
The amount of titanium tetrahalide (d) may vary a lot and depends e.g. on the manner of contacting it with said intermediate (abc). If the titanium tetrahalide is added to the intermediate or magnesium compound, a large stoichiometric excess thereof is not needed. Within the scope of the claimed process, the amount of titanium tetrahalide may be optimized to give a suitable catalyst. Most preferably, in step (iii), said intermediate (abc) is added into and reacted with said titanium tetrahalide (d) in a molar ratio Mgtotal added/(d) of between 1:100 and 1:1, preferably between about 1:50 and about 1:5, most preferably about 1:10.
In the reaction sequence (i)xe2x86x92(iii), it is preferable if in step (iii), said intermediate (abc), more preferably a solution thereof, is added slowly, most preferably dropwise, to said titanium tetrahalide (d) to form a solution of said catalyst component.
Thereby, the titanium tetrahalide is preferably hot, most preferably at 110xc2x0 C. The best results are obtained, if in step (iii), a toluene solution of said intermediate (abc) is added dropwise to said titanium tetrahalide (d) at 110xc2x0 C. The preferred reaction time is about 5 min to about 20 min, most preferably about 10 min.
After the reaction sequence (i)xe2x86x92(ii)xe2x86x92(iii), the reaction product, which is a precursor of, or a crude version of said catalyst component, is recovered in a recovery step (iv). Preferably, said catalyst component is recovered by continously heating a solution of said catalyst component, most preferably said toluene solution of said catalyst component, for the precipitation of the catalyst component in crude form or a precursor thereof and allowing it to settle. Immediately before said precipitation, preferably a C5-C10 hydrocarbon solvent, more preferably toluene, most preferably toluene in a molar ratio Mgtotal added/toluene of about 1:10 to about 1:100, is added to the catalyst component solution. After the crude catalyst component or the precursor has settled, the supernatant liquid is removed e.g. by decantering or siphoning.
After the recovery step (iv), said catalyst component in crude form or said precursor is optionally washed in a washing step (v). By precursor is meant a reaction product, which still is not in the form of the final catalyst component. This state of things derives from the nature of the reaction product, which may be a larger complex (see definition above) consisting of or containing one or several molecules and/or smaller complexes. Because of the loose structure of such a larger complex or complex mixture, washing will remove some of the complexes and/or molecules and essentially change the composition of the remaining solid product.
It is preferable if, in step (v), said recovered crude catalyst component or its precursor is washed with toluene, preferably with hot (e.g. 90xc2x0 C.) toluene. It is also preferable, if in step (v), said recovered crude catalyst component, said recovered catalyst component precursor or said preliminary washed catalyst component is washed with heptane, most preferably with hot (e.g. 90xc2x0 C.) heptane. Further, it is preferable, if in step (v), said recovered crude catalyst component, said recovered catalyst component precursor or said preliminary washed catalyst component is washed with pentane. A washing step (v) typically includes several substeps which gradually increase the magnesium dihalide content of the catalyst precursor. Such a washing sequence is, for example, one wash with toluene at 90xc2x0 C., two washes with heptane at 90xc2x0 C. and one wash with pentane at room temperature.
The washing can according to the invention be optimized to give a catalyst with novel and desirable properties. Thus in step (v), said recovered catalyst component is preferably washed to give the following ratio of said magnesium dihalide, said titanium tetrahalide, and said dicarboxylic acid ester as internal electron donor ED (3):
(MgX2)8-10(Tixxe2x80x34)1(ED)0.7-1.3xe2x80x83xe2x80x83(3)
wherein MgX2 is said magnesium dihalide, TiXxe2x80x34 is said titanium tetrahalide and ED is said dicarboxylic acid ester as internal electron donor, preferably a phthalic acid di-, oligo- or polyester. X and Xxe2x80x3 are both preferably Cl.
Finally, the washed catalyst component is usually dried, preferably by evaporation.
In appendices 1 and 2 are described the schemes of four embodiments of the present invention; two starting from a magnesium dihalide MgX2 and two starting from a dialkyl magnesium R2Mg.
In addition to the above described process, the invention also relates to an olefin polymerization catalyst component comprising a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- or polyester as internal electron donor ED, which has been prepared according to the above described process. By said catalyst component is meant the so called procatalyst component, i.e. the transition metal component of the whole olefin catalyst system, which system additionally includes a so called cocatalyst, i.e. an organic compound of a non-transition metal, and optionally a so called external electron donor
An advantageous embodiment of the catalyst component according to the invention comprises a magnesium dihalide, a titanium tetrahalide, and a dicarboxyl acid ester as internal electron donor ED, is essentially homogenous and has the following ratio of said magnesium dihalide, said titanium tetrahalide, and said dicarboxylic acid ester as internal electron donor ED (3):
(MgX2)8-10(TiXxe2x80x34)1(ED)0.7-1.3xe2x80x83xe2x80x83(3)
wherein MgX2 is said magnesium dihalide, TiX4 is said titanium tetrahalide and ED is said dicarboxylic acid ester as internal electron donor, preferably a phthalic acid di-, oligo- or polyester. Preferably Xxe2x95x90Xxe2x80x3xe2x95x90Cl. Most preferably, the catalyst component is a complex having the formula (3). This composition gives the highest activity, and when using in its preparation a polyol Rxe2x80x2(OH)m, wherein Rxe2x80x2 is an m-valent C1-C20 hydrocarbyl group and m is an integer selected from 2, 3, 4, 5 and 6, its morphology can conveniently be adjusted to give olefin polymers of various desired particle sizes and particle size distributions (PSD).
When adding during the preparation process of the claimed catalyst component a reactive halogenated hydrocarbon (e) of the formula (2)
Rxe2x80x2xe2x80x3Xxe2x80x2xe2x80x3nxe2x80x83xe2x80x83(2)
wherein Rxe2x80x2xe2x80x3 is an n-valent C1-C20 hydrocarbyl group, Xxe2x80x2xe2x80x3 is a halogen and n is an integer selected from 1, 2, 3 and 4, the product will preferably contain more halogen than was to be expected on the basis of the MgX2 and TiX4 present. Preferably, the claimed catalyst component might contain halogen from about 10% to about 60% more than the amount of halogen calculated on the basis of the amounts of magnesium and titanium present, assuming that all of the magnesium is in the form of said MgX2 and essentially all of the titanium is in the form of said TiX4.
In the claimed catalyst component, the magnesium halide (Xxe2x95x90Cl) structure has an X-ray diffraction pattern which differs from the X-ray diffraction pattern of pure MgCl2. It preferably shows an X-ray diffraction pattern with a lamellar thickness indicating peak at 17xc2x0 2"THgr", showing a clear position shift compared to normal amorphous MgCl2 which gives a height indicating peak at 15xc2x0 2"THgr". Indeed, according to J. Dorrepaal et al. (J. Appl.Crystallography, 1984 17, page 483), the crystal structure of MgCl2 is characterized by a=3,640 xc3x85 and C=17,673 xc3x85. In an X-ray diffraction pattern the peak at about 15xc2x0 2"THgr" is in the direction (003) of the c-axis, i.e. describing the height to the hexagonal unit cell, when Cu Kxcex1 radiation is used.
In addition to the above described process and catalyst component, the invention also relates to a process for the polymerization of olefins. The process is characterized by the steps of
(A) preparing a catalyst component according to the above defined process,
(B) feeding to at least one polymerization reactor said catalyst component, as well as a cocatalyst, which has the formula (4)
RpAlrX3r-pxe2x80x83xe2x80x83(4)
wherein R is a C1-C10 alkyl, preferably a C1-C4 alkyl, most preferably ethyl, X is a halogen, preferably chlorine, p is an integer from 1 to (3rxe2x88x921), preferably 2 or 3, most preferably 3, and r is I or 2, preferably 1, the molar ratio between said catalyst component and said cocatalyst, expressed as Al/Ti, preferably being 10-2000, more preferably 50-1000, most preferably 200-500,
optionally an external electron donor, which preferably is a silane, more preferably a C1-C12 alkyl-C1-C12 alkoxy silane, most preferably cyclohexyl methyl dimethoxy silane,
optionally a C4-C10 hydrocarbon solvent, preferably pentane, hexane and/or heptane,
preferably a chain transfer agent, which is hydrogen, and
at least one olefin monomer, which preferably is propene,
(C) carrying out the polymerization of said olefin monomer in said at least one polymerization reactor to give an olefin polymer (=homopolymer or copolymer) and
(D) recovering said olefin polymer.
In the claimed olefin polymerization process, the used (transition metal) catalyst component can be prepared according to any above described embodiment of the catalyst component preparation process.
According to one further embodiment of the invention, olefins are polymerized by the steps of
(A) providing a solid olefin polymerization catalyst component which is essentially homogenous and comprises a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- or polyester as internal electron donor ED in the following ratio (3):
(MgX2)8-10(TiXxe2x80x34)1(ED)0.7-1.3xe2x80x83xe2x80x83(3)
wherein MgX2 is said magnesium dihalide, TiXxe2x80x34 is said titanium tetrahalide, X and/or Xxe2x80x3 is preferably Cl, and ED is said dicarboxylic acid di-, oligo- or polyester as internal donor, preferably a phthalic acid di-, oligo- or polyester,
(B) feeding to at least one polymerization reactor said catalyst component, as well as a cocatalyst which has the formula (4)
RpAlrX3r-pxe2x80x83xe2x80x83(4)
wherein R is a C1-C10 alkyl, preferably a C1-C4 alkyl, most preferably ethyl, X is a halogen, preferably chlorine, p is an integer from 1 to (3rxe2x88x921), preferably 2 or 3, most preferably 3, and r is 1 or 2, preferably 1, the molar ratio between said catalyst component and said cocatalyst, expressed as Al/Ti, preferably being 10-2000, more preferably 50-1000, most preferably 200-500,
optionally an external electron donor, which preferably is a silane, more preferably a C1-C12 alkyl-C1-C12 alkoxy silane, most preferably cyclohexyl methyl dimethoxy silane,
optionally a C4-C10 hydrocarbon solvent, preferably pentane, hexane and/or heptane,
preferably a chain transfer agent, which is hydrogen, and
at least one olefin monomer, which preferably is propylene, (C) carrying out the polymerization of said olefin monomer in said polymerization reactor to give an olefin polymer (=homopolymer or copolymer) and
(D) recovering said olefin polymer.
The invention is described below by means of examples, the purprose of which merely is to illustrate the invention.